Question for the Omark experts

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KHGS
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Re: Question for the Omark experts

#16 Postby KHGS » Tue Aug 28, 2018 8:18 am

Pommy Chris wrote:
Bigtravoz wrote:
Pommy Chris wrote:Dont own use an Omark anymore, long since moved up the food chain, but, with 155's my load was at the time very low, I was only doing 2930 as I was just using it at the club out to 600 yards. I cant remember my loads but it was something like 43 or 43 grains of 2208. Anyway I ended up with circles on by brass due to removed ejector so it does not have to be a hot load to do it.
Chris

43 of 2208 would be merely dribbling out the end of the barrel, I reckon 2930 would be a bit hotter than that.

Not with the rather tight Archer barrels that were for sale at the time, that was the speed.
Chris


Velocity & pressure do not always go hand in hand. Some barrels will develop pressure at lower velocities. If you have brass flow into the ejector hole, plunger in or out, you have pressure, or soft brass!!!
Keith H.

Pommy Chris
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Re: Question for the Omark experts

#17 Postby Pommy Chris » Tue Aug 28, 2018 8:41 am

KHGS wrote:
Pommy Chris wrote:
Bigtravoz wrote:43 of 2208 would be merely dribbling out the end of the barrel, I reckon 2930 would be a bit hotter than that.

Not with the rather tight Archer barrels that were for sale at the time, that was the speed.
Chris


Velocity & pressure do not always go hand in hand. Some barrels will develop pressure at lower velocities. If you have brass flow into the ejector hole, plunger in or out, you have pressure, or soft brass!!!
Keith H.

I really dont think there is pressure at 2930 with 155's and 42 grains of 2208, sorry no way. If thre was pressure there would have been obvious signs ie flattened primers etc and there was not Also since used same barrel rechambered on my Barnard with 185's doing 2828 with no pressure issues at all. The ejector hole is very large so a lot of brass unsupported. It does not take any special pressures in an Omark to make a mark in the brass. Actually I have never seen anyone's Omark brass (who has the ejector hole) without a mark on the brass.
CHris

bainp
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Re: Question for the Omark experts

#18 Postby bainp » Tue Aug 28, 2018 8:55 am

I used Sportco/Omark M44 rifles for 30+ years without the ejector. The last lot of brass I used was Lapua LR primer fitted, had something like 20 firings from each case before I retired it because the case head could no longer be sized down to fit easily in the chamber. That brass never showed any sign of a mark from the ejector hole. You can shoot competitively without loading to pressures where you get brass flow!
I agree entirely with Keith.
Philip

Barry Davies
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Re: Question for the Omark experts

#19 Postby Barry Davies » Tue Aug 28, 2018 9:42 am

Agree with Keith and Phil.
Overloading will cause brass " flow " with or without an ejector. Moderate loads do NOT cause brass " flow " unless you have soft brass caused by incorrect annealing.
Barry

Pommy Chris
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Re: Question for the Omark experts

#20 Postby Pommy Chris » Tue Aug 28, 2018 2:07 pm

Barry Davies wrote:Agree with Keith and Phil.
Overloading will cause brass " flow " with or without an ejector. Moderate loads do NOT cause brass " flow " unless you have soft brass caused by incorrect annealing.
Barry

At the time was shooting large rifle primer Lapua and there was marks from the ejector and I dont think it is uncommon either as seen it a lot. Remember Omarks are not exactly well made, the marking may depend on the rifle and the hole itself. That said from my experience no way is it possible to get no marking at all on Brass on an Omark with ejector removed.
Chris

Malcolm Hill
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Re: Question for the Omark experts

#21 Postby Malcolm Hill » Wed Aug 29, 2018 8:07 am

Chris. I have and still use several Omarks. I don't like having ejectors in target rifles so all of mine have had the ejector springs replaced with very weak ones that still leave it in place but not functional as an ejector. The reason I do this is to leave the design of the action and bolt head unchanged in regard to gas escape in the event of a pieced primer or such. In the many thousands of rounds that have been fired through them I have never had any issues with brass flow into the ejector hole showing up on case heads (223 or 308). My 223 loads are all just on or over 3000 fps.(checked with Labradar and Oehler equipment). Even with bolt heads that have been converted from 308 where an ejector pin can't be fitted or used due to location from centre this issue has never been a problem. As Keith said the only cause of the ring appearing is excess pressure flowing the brass in the case head. No other reason. Regards Malcolm.

Pommy Chris
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Re: Question for the Omark experts

#22 Postby Pommy Chris » Wed Aug 29, 2018 8:26 am

Malcolm Hill wrote:Chris. I have and still use several Omarks. I don't like having ejectors in target rifles so all of mine have had the ejector springs replaced with very weak ones that still leave it in place but not functional as an ejector. The reason I do this is to leave the design of the action and bolt head unchanged in regard to gas escape in the event of a pieced primer or such. In the many thousands of rounds that have been fired through them I have never had any issues with brass flow into the ejector hole showing up on case heads (223 or 308). My 223 loads are all just on or over 3000 fps.(checked with Labradar and Oehler equipment). Even with bolt heads that have been converted from 308 where an ejector pin can't be fitted or used due to location from centre this issue has never been a problem. As Keith said the only cause of the ring appearing is excess pressure flowing the brass in the case head. No other reason. Regards Malcolm.

Dont know Malcolm, I checked Betta's Omark 223 which we still have and no circles on the brass, but it did on the 308 with very mild loads.
Chris

David B
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Re: Question for the Omark experts

#23 Postby David B » Wed Aug 29, 2018 10:48 am

If the case is over sized or head space too loose mild loads could be slamming the case against the bolt face, but as Keith has said it has nothing to with the ejector missing. filling the hole would just mask a problem.

Pommy Chris
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Re: Question for the Omark experts

#24 Postby Pommy Chris » Wed Aug 29, 2018 3:06 pm

David B wrote:If the case is over sized or head space too loose mild loads could be slamming the case against the bolt face, but as Keith has said it has nothing to with the ejector missing. filling the hole would just mask a problem.

Ahh maybe that is it, at the time I had just started shooting and I was full length resizing maybe that was making the marks, that said as I said before I have seen lots of Omarks with this mark on the brass from guys using normal loads.
Chris

Bigtravoz
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Re: Question for the Omark experts

#25 Postby Bigtravoz » Fri Aug 31, 2018 8:32 pm

Just to be safe and alleviate everyone’s thoughts of the possibilities of case damage and venting of ruptured case gases I made a plug with similar tolerances to the ejector that sits just below flush with the bolt face (1 thou below) will see how it goes tomorrow.

KHGS
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Re: Question for the Omark experts

#26 Postby KHGS » Sat Sep 01, 2018 9:08 am

Bigtravoz wrote:Just to be safe and alleviate everyone’s thoughts of the possibilities of case damage and venting of ruptured case gases I made a plug with similar tolerances to the ejector that sits just below flush with the bolt face (1 thou below) will see how it goes tomorrow.
!

So that will allow a .001" brass flow with hot loads or soft brass!!!
Keith H. :) :) :)

Bigtravoz
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Re: Question for the Omark experts

#27 Postby Bigtravoz » Sat Sep 01, 2018 9:32 am

KHGS wrote:
Bigtravoz wrote:Just to be safe and alleviate everyone’s thoughts of the possibilities of case damage and venting of ruptured case gases I made a plug with similar tolerances to the ejector that sits just below flush with the bolt face (1 thou below) will see how it goes tomorrow.
!

So that will allow a .001" brass flow with hot loads or soft brass!!!
Keith H. :) :) :)


If 1 thou allows brass to “flow” so be it! That’s such an incorrect term! If it was going to expand to fill the one thou depression it would more than definitely have been able to depress the ejector deeper than that.

KHGS
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Re: Question for the Omark experts

#28 Postby KHGS » Sat Sep 01, 2018 6:57 pm

Bigtravoz wrote:
KHGS wrote:
Bigtravoz wrote:Just to be safe and alleviate everyone’s thoughts of the possibilities of case damage and venting of ruptured case gases I made a plug with similar tolerances to the ejector that sits just below flush with the bolt face (1 thou below) will see how it goes tomorrow.
!

So that will allow a .001" brass flow with hot loads or soft brass!!!
Keith H. :) :) :)


If 1 thou allows brass to “flow” so be it! That’s such an incorrect term! If it was going to expand to fill the one thou depression it would more than definitely have been able to depress the ejector deeper than that.


What I & others have been saying!! What is the incorrect term that you refer to?
Keith H.

Barry Davies
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Re: Question for the Omark experts

#29 Postby Barry Davies » Sat Sep 01, 2018 7:19 pm

Light loads in tight barrels can cause " secondary " pressures which results in a spike caused by the high pressure gases catching up with the projectile prior to exit. Once thought not to exist but has since been proven to be there under certain circumstances -- light loads in tight barrels being one of them. It takes a LOT of pressure to have a case flow back into the ejector hole --Omark or any other action.
Barry

Bigtravoz
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Re: Question for the Omark experts

#30 Postby Bigtravoz » Thu Sep 06, 2018 7:23 am

KHGS wrote:
Bigtravoz wrote:
KHGS wrote:!

So that will allow a .001" brass flow with hot loads or soft brass!!!
Keith H. :) :) :)


If 1 thou allows brass to “flow” so be it! That’s such an incorrect term! If it was going to expand to fill the one thou depression it would more than definitely have been able to depress the ejector deeper than that.


What I & others have been saying!! What is the incorrect term that you refer to?
Keith H.


The incorrect term I was talking about is brass flowing. It isn’t water it doesn’t flow.


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